From 9e58b81851f1b6614b3160443b519c19823b4b54 Mon Sep 17 00:00:00 2001
From: Franklin Wang <9077461+gnawf@users.noreply.github.com>
Date: Thu, 21 Dec 2023 15:29:48 +1300
Subject: [PATCH] Prevent multiple source fields even if list is not leaf field
 (#503)

* Prevent multiple source fields even if list is not leaf field

* Rename var
---
 .../validation/NadelHydrationValidation.kt    | 36 ++++----
 .../NadelHydrationValidationTest2.kt          | 91 +++++++++++++++++++
 2 files changed, 110 insertions(+), 17 deletions(-)

diff --git a/lib/src/main/java/graphql/nadel/validation/NadelHydrationValidation.kt b/lib/src/main/java/graphql/nadel/validation/NadelHydrationValidation.kt
index fe68ff685..3c61d5e9e 100644
--- a/lib/src/main/java/graphql/nadel/validation/NadelHydrationValidation.kt
+++ b/lib/src/main/java/graphql/nadel/validation/NadelHydrationValidation.kt
@@ -8,6 +8,7 @@ import graphql.nadel.dsl.RemoteArgumentSource.SourceType.ObjectField
 import graphql.nadel.dsl.RemoteArgumentSource.SourceType.StaticArgument
 import graphql.nadel.dsl.UnderlyingServiceHydration
 import graphql.nadel.engine.util.getFieldAt
+import graphql.nadel.engine.util.getFieldsAlong
 import graphql.nadel.engine.util.isList
 import graphql.nadel.engine.util.isNonNull
 import graphql.nadel.engine.util.partitionCount
@@ -120,30 +121,31 @@ internal class NadelHydrationValidation(
         hydrations: List<UnderlyingServiceHydration>,
     ): List<NadelSchemaValidationError> {
         if (hydrations.size > 1) {
-            val anyListSourceInputField = hydrations
-                .any { hydration ->
-                    val parentType = parent.underlying as GraphQLFieldsContainer
+            val pathsToSourceFields = hydrations
+                .asSequence()
+                .flatMap { hydration ->
                     hydration
                         .arguments
                         .asSequence()
-                        .mapNotNull { argument ->
-                            argument.remoteArgumentSource.pathToField
-                        }
-                        .any { path ->
-                            parentType.getFieldAt(path)?.type?.unwrapNonNull()?.isList == true
+                        .mapNotNull { it.remoteArgumentSource.pathToField }
+                }
+                .toList()
+
+            val parentType = parent.underlying as GraphQLFieldsContainer
+            val anyListSourceInputField = pathsToSourceFields
+                .any { pathToField ->
+                    parentType
+                        .getFieldsAlong(pathToField)
+                        .any { field ->
+                            field.type.unwrapNonNull().isList
                         }
                 }
 
             if (anyListSourceInputField) {
-                val sourceFields = hydrations
-                    .flatMapTo(LinkedHashSet()) { hydration ->
-                        hydration.arguments
-                            .mapNotNull { argument ->
-                                argument.remoteArgumentSource.pathToField
-                            }
-                    }
-
-                if (sourceFields.size > 1) {
+                val uniqueSourceFieldPaths = pathsToSourceFields
+                    .toSet()
+
+                if (uniqueSourceFieldPaths.size > 1) {
                     return listOf(
                         NadelSchemaValidationError.MultipleHydrationSourceInputFields(parent, overallField),
                     )
diff --git a/lib/src/test/kotlin/graphql/nadel/validation/NadelHydrationValidationTest2.kt b/lib/src/test/kotlin/graphql/nadel/validation/NadelHydrationValidationTest2.kt
index d8c2265d2..fe6627343 100644
--- a/lib/src/test/kotlin/graphql/nadel/validation/NadelHydrationValidationTest2.kt
+++ b/lib/src/test/kotlin/graphql/nadel/validation/NadelHydrationValidationTest2.kt
@@ -170,6 +170,97 @@ class NadelHydrationValidationTest2 {
         assertTrue(errors.single().subject.name == "data")
     }
 
+    @Test
+    fun `prohibit multiple source fields where list not the leaf`() {
+        val fixture = NadelValidationTestFixture(
+            overallSchema = mapOf(
+                "activity" to /* language=GraphQL*/ """
+                    type Query {
+                        myActivity: [Activity]
+                    }
+                    union ActivityContent = User | Issue
+                    type Activity {
+                        id: ID!
+                        data: [ActivityContent]
+                        @hydrated(
+                            service: "users"
+                            field: "usersByIds"
+                            arguments: [
+                                {name: "ids", value: "$source.contexts.userId"}
+                            ]
+                        )
+                        @hydrated(
+                            service: "issues"
+                            field: "issuesByIds"
+                            arguments: [
+                                {name: "ids", value: "$source.contexts.issueId"}
+                            ]
+                        )
+                    }
+                """.trimIndent(),
+                "users" to /* language=GraphQL*/ """
+                    type Query {
+                        usersByIds(ids: [ID]!): [User]
+                    }
+                    type User {
+                        id: ID!
+                        name: String!
+                    }
+                """.trimIndent(),
+                "issues" to /* language=GraphQL*/ """
+                    type Query {
+                        issuesByIds(ids: [ID]!): [Issue]
+                    }
+                    type Issue {
+                        id: ID!
+                        key: String
+                    }
+                """.trimIndent(),
+            ),
+            underlyingSchema = mapOf(
+                "activity" to /* language=GraphQL*/ """
+                    type Query {
+                        myActivity: [Activity]
+                    }
+                    type ActivityContext {
+                        issueId: ID
+                        userId: ID
+                    }
+                    type Activity {
+                        id: ID!
+                        contexts: [ActivityContext]
+                    }
+                """.trimIndent(),
+                "users" to /* language=GraphQL*/ """
+                    type Query {
+                        usersByIds(ids: [ID]!): [User]
+                    }
+                    type User {
+                        id: ID!
+                        name: String!
+                    }
+                    type Account {
+                        id: ID!
+                    }
+                """.trimIndent(),
+                "issues" to /* language=GraphQL*/ """
+                    type Query {
+                        issuesByIds(ids: [ID]!): [Issue]
+                    }
+                    type Issue {
+                        id: ID!
+                        key: String
+                    }
+                """.trimIndent(),
+            ),
+        )
+
+        val errors = validate(fixture)
+        assertTrue(errors.map { it.message }.isNotEmpty())
+        assertTrue(errors.single() is NadelSchemaValidationError.MultipleHydrationSourceInputFields)
+        assertTrue(errors.single().subject.name == "data")
+    }
+
     @Test
     fun `prohibit mixing list and non-list source input fields`() {
         val fixture = NadelValidationTestFixture(